Intelligent optimum-gear indication system

ABSTRACT

A method and a circuit for determining the optimum gear, in terms of fuel consumption, of a motor vehicle drive is proposed, in which after upshifting, a driving power sufficient for accelerating the vehicle is to be made available regardless of such power parameters as total vehicle weight, roadway grades and the like and also regardless of the gear ratios of the gear steps. To this end, during driving, the gear ratios of the gear steps are ascertained by comparing the speeds (n, n 1 ) before and after the transmission (12). Furthermore, these speed values (n, n 1 ) as well as the gas pedal position (φ) are continuously stored briefly in memory during the drive, and a standardized power is ascertained based on the change in the driving speed (n 1 ). After a gear shifting operation, the newly ascertained standardized power is compared with the standardized power ascertained prior to shifting, and if the new standardized power is the same or greater, the values for the driving speed (n 1 ) and gas pedal position (φ) measured prior to the upshifting are recorded in a threshold value memory (24). An upshifting indication is always effected whenever the instantaneous measured values (n 1 , φ) exceed the stored threshold values in the direction of an unfavorable operating range in terms of fuel consumption. The method is applicable to both Diesel and gasoline engines as well as to large and small motors and to any arbitrary, but fixed, gear step ratios.

The invention relates to a method for determining the optimal gear, interms of fuel consumption, of a motor vehicle drive which adapts itselfas it learns how the vehicle responds to the particular driver, roadconditions, and engine condition encountered during a drive. Theinvention also relates to a circuit for performing the method.

BACKGROUND

In a known circuit arrangement for controlling a gear shift indicator ofa motor vehicle drive, threshold limit values, ascertained for each gearby the vehicle manufacturer, for shifting into the next-higher gear arefed into an electronic read-only memory. During vehicle operation, thespeed values and gas pedal positions that are ascertained on acontinuous basis are compared with the threshold or limit values in acomputer, and if the limit values are exceeded, a signal for shifting toa higher gear is triggered (German Patent Disclosure Document, laid openNo. DE OS 31 28 080 Feb. 3, 1983). This arrangement has the disadvantagethat the threshold or limit values must be ascertained for each vehicletype in accordance with the gear ratios of the gear steps and inaccordance with the engine's power rating, based on an assumption thatthe engine is optimally tuned. Since after breaking in, engines mayalready have considerable fluctuations in power as compared with therated value, and since in the course of time further power fluctuationsare brought about by adjustments of the ignition or the carburetor orfuel injection pump, the threshold values ascertained by themanufacturer for gear shifting may be only approximate values.Furthermore, this method does not take into consideration changing loadconditions or the grade of the roadway while driving when indicating ashift into a higher gear.

With the present invention, the object is to develop a method fordetermining the threshold values for shifting gears which enablesoptimum power at minimum fuel consumption, regardless of the size of theengine, the vehicle load or the gear ratios.

THE INVENTION

The method according to the invention for determining the optimum gearfor fuel consumption has the advantage that the limit or thresholdvalues, of gas pedal position and engine speed that are required forshifting gears, are ascertained only after the circuit has beeninstalled in the motor vehicle and during a first distance driven.Consequently, such a system is generally applicable in all vehicletypes, without having to make any adaptations or changes. It determinesthe vehicle-specific and hence correspondingly accurate threshold valuesfor fuel consumption-optimal gear shifting, and after the shifting hasbeen done at least the same power can be made available by the drivingmotor as before. A further advantage is that in accordance with themethod according to the invention and the circuit required for it, thedriving performance of the driver is also taken into consideration indetermining the threshold or limit values. By measuring a so-calledstandardized power prior to and following gear shifting, differentthreshold values will be determined and stored in memory in the case ofa skilled driver, who needs only a short time for shifting, than in thecase of a driver who needs a longer time to shift into the new gear.

Briefly, it is particularly advantageous if for each gear, in the areaof a threshold value memory associated with it, the threshold valuesthat have been determined are stored in a memory matrix laid out insteps in accordance with the engine speed and the gas pedal position.After the threshold values have been determined and stored in memory,the instantaneous values for engine speed and gas pedal position arecompared with the threshold value for the gear presently engaged thatare stored in the threshold value memory, so that a signal forupshifting can be triggered whenever the instantaneous values exceed thethreshold values in the direction of an operating zone that isunfavorable in terms of fuel consumption.

The circuit for performing the method, has the advantage that alreadyprovided transducers for measuring engine speed and the gas pedalposition can also be used for the circuit, and that practically anyvehicle can be retrofitted with such a circuit. The evaluation circuitis preferably implemented using a microcomputer, to the output of whichan upshifting indicator is connected.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is shown in the drawing andexplained in further detail in the ensuing description. Shown are:

FIG. 1, a motor vehicle represented symbolically, with a block circuitdiagram of the circuit for performing the method according to theinvention;

FIG. 2, a flow diagram for a computer in the circuit according to FIG. 1for determining the threshold values and for triggering an upshiftingindication;

FIG. 3, a threshold value characteristic curve of the threshold valuememory of FIG. 1 for one gear; and

FIG. 4, power curves for the drive motor of the motor vehicle.

DETAILED DESCRIPTION:

In FIG. 1, a motor vehicle, arbitrarily shown symbolically, is marked10, and an internal combustion engine, as its drive motor 11, isinstalled in it. The drive motor 11 is coupled with two drive wheels 14of the motor vehicle via a disengageable, shiftable multi-steptransmission 12 and a differential 13. A gas pedal, 15 that is to beactuated by the driver using his foot, is connected, via a mechanicaloperative connection shown in broken lines, to a throttle 16 in thein-take tube 17 of the drive motor 11. The gas pedal 15 also acts in aknown manner upon a fuel supply means, not shown, such as a carburetoror injection pump of the drive motor 11. A position transducer 18sensing the position of the gas pedal 15 or throttle 16 is electricallyconnected to the input of a microcomputer 19 of an evaluation circuitdevice 10. A transducer 21 between the motor 11 and transmission 12which senses the speed n of the drive motor 11 is also connected to oneinput of the microcomputer 19. Via a third transducer 22 at the outputof the transmission 12, the output speed n₁ of the transmission 12 issensed and likewise sent to an input of the microcomputer 19. The speedvalue n₁ is at the same time a value for the driving speed or movingspeed of the vehicle 10. Also connected to the microcomputer 19 are atransient memory 23, as a short term memory, and a threshold valuememory 24, which is subdivided in turn into individual ranges for eachgear, each comprising one memory matrix 24a. No range is provided in thethreshold value memory, however, for reverse gear or for the highestgear. An upshift indicator 25 is connected to the output of themicrocomputer 19 and generates a visual signal whenever the drive motor11 is capable of operating more economically at a higher gear of themulti-step transmission.

The method for determining the optimal gear in terms of fuel consumptionand the mode of operation of the circuit provided therefor and shown inFIG. 1 will now be described in further detail, referring to the flowdiagram of FIG. 2 and the characteristic curves of FIGS. 3 and 4. Whenthe vehicle 10 is started up, first the gear ratios of the gear stepsare ascertained, and then the threshold values are determined and storedin memory for each gear, with the exception of the highest gear.Finally, during the drive, data are continuously compared with thethreshold values and an upshifting indication is triggered as needed.

When the motor vehicle electrical system is started, the first operationafter the start 49 of the computer program is a checking step 30 as towhether the starting switch for the engine has been switched on. Via aloop, the program remains at this program step until such time as thecurrent circuits required for driving have finally been switched on. Inthe next step 31, the engine speed n and the output speed n₁ of thetransmission 12 are sensed. If both values are greater than zero, thenthe the engine is running and the vehicle is in operation. In the nextstep 32, the ratio between the speeds n and n₁ is determined and thetranslation ratio of the gear that is engaged is accordinglyascertained. In step 33, the value determined repeatedly over a briefperiod of time is recorded in a register, and a register counter isincreased by 1. The number of occupied register locations corresponds tothe number of gears in the transmission 12. In a further step 34, theregister contents are arranged by magnitude as needed, so that theindividual gears g are associated with the registers in ascending order.With the engine 11 running, the measured speed values n, n₁, the value φfor the gas pedal position and the engaged gear g are now, in step 35,stored in the short-term memory 23, for instance for a period of 10seconds. In the next step 36, by a comparison of the speed values n andn₁, it is determined whether gear shifting in the transmission 12 hasbeen performed. If the two speed values are no longer in a fixed ratiowith one another, this is the case. In the next step 37, the values mostrecently stored in the short-term memory 23 are then called up and fedinto an intermediate or buffer memory of the microcomputer 19. In thenext step 38, a value which will be called herein a standardized powerPn is determined, on the basis of the output speed n₁ over time; in sodoing, the difference among the squared values of the speeds n₁ measuredin quick succession at the transmission output is determined. Thestandardized power prior to the gear shifting operation is determined inthe microcomputer 19 in accordance with the following algorithm:

    Pn=n.sub.1a.sup.2 -n.sub.1b.sup.2.

The value n_(1a) is the speed measured most recently prior to theshifting operation, and the value n_(1b) is the speed measured forinstance 2 seconds earlier than that. Both values are taken from theshort-term memory 23. In step 39, by comparing the speeds n and n₁, itis now determined whether the upshifting operation in the transmissionhas been completed. As soon as that is the case, a check is made in thenext step 40 as to whether the transmission 12 was shifted into the nexthigher gear (g+1). If that is the case, then in step 41 further speedvalues n, n₁ as well as the gas pedal position φ and the engaged gearare stored in the short-term memory 23. After three seconds, in step 42,the new standardized power Pn2 is determined; this value appears afterthe upshifting of the transmission. For this calculation, the mostrecently measured speed value n_(1c) as well as the speed value n_(1d)measured 2 seconds previously are taken from the short-term memory 23and used, and the standardized power is determined as follows:

    Pn.sub.2 =n.sub.1c.sup.2 -n.sub.1d.sup.2.

In the next step 43, it is now determined whether the standardized powerPn₂ measured after upshifting of the transmission 12 is equal to orgreater than the standardized power Pn₁ prior to the upshiftingoperation. If that is the case, then the actual drive power of thevehicle has not been decreased by the upshifting operation; in otherwords, the upshifting has proceeded successfully.

By means of the so-called standardized power Pn, the influence ofvarious power parameters such as vehicle weight, roadaway upgrades, airand frictional resistance, tire pressure etc., deviations from ratedengine power, skilled or unskilled drivers, fuels of varying quality andso forth are eliminated. It is merely assumed that these parameters areof equal magnitude prior to and following the upshifting operation. Nowif the standarized power following the upshifting is equal to or greaterthan prior to the shifting operation, then along with the upshifting,the fuel consumption of the vehicle per unit of time has been reduced,with the same power and consequently the same moving speed. Care must betaken to assure that in future shifting operations, an upshiftingindication is always triggered whenever, during the drive, the engine11, in the same gear g, reattains the working point assumed mostrecently prior to the upshifting. FIG. 3 shows such a working point A1by way of example for upshifting from second gear in the transmission12; this point is determined from the value of the measured engine speedn of 2000 min⁻¹ and the value of the measured gas pedal position φ inangular degrees of 30°. The working point A1 represents an at leasttemporary threshold for upshifting of the transmission. This thresholdvalue must consequently be fed in the next program step 44 into thememory matrix 24a of the threshold value memory 24 for second gear. Thebinary memory matrix 24a of the threshold value memory 24 is laid out infine gradations into individual memory locations, in rows according toangular ranges for the gas pedal position φ and in columns according tospeed ranges of the engine speed n. The working point A1 of FIG. 3 isnow fed into the region of the threshold value memory 24 for second gearin such a manner that a "1" is recorded in all the memory locationsabove the speed n of 2000 min⁻¹ and below the gas pedal position φ of30°. All the other memory locations retain an "0" as their initialcontent.

Upon a later upshifting out of second gear without any power loss, asecond working point A2 is ascertained as a threshold value in the samemanner, as shown in FIG. 3, and recorded into the region of thethreshold value memory 24 for second gear, in that all the memorylocations above a speed n of 4600 and below a gas pedal position φ of54° are assigned a content of "1". In this manner, within the first 10to 100 km of driving, sufficient threshold values are recorded in thememory matrices 24a of the threshold memory 24 as to form one operatingzone I having memory locations with the content "0" for an engineoperating state that is favorable in terms of fuel consumption and oneoperating zone II comprising memory locations having the content "1" foran engine operating state that is unfavorable in terms of fuelconsumption in each memory matrix 24a of the threshold value memory 24.Both operating zones I and II are shown separately in FIG. 3, divided bya threshold value curve a.

In a further program segment shown in FIG. 2, there is continuousmonitoring, with a gear engaged, as to whether the fuel consumption canbe reduced, at the instantaneous drive output, by upshifting of thetransmission. To this end, in program step 45, the instantaneous workingpoint A of the engine 11 is first ascertained from the engaged gear gand the values for speed n and gas pedal position φ. In the next step46, it is determined whether the ascertained working point A is withinthe unfavorable fuel consumption zone II of the corresponding memorymatrix 24a of the threshold value memory 4 in which the memory locationshave a content of "1". As soon as that becomes the case, in step 47,after a waiting period of approximately 3 seconds, a signal is sent fromthe microcomputer 19 to the upshifting indicator 25 (FIG. 1), therebyinstructing the driver to shift the transmission to a higher gear. Inthe next program step 48, a check is made as to whether the ignitionswitch is OFF and hence whether the motor is shut off. As soon as thisoccurs, at the end of the drive, the end 50 of the program is reached.

However, as long as the ignition switch is still ON, the program returnsafter program step 48 back to program step 31, as indicated by thesymbols III--III in FIG. 2, so as once again, in the above-describedmanner, to determine the engaged gear and to record new values for thespeeds n, n₁, the gas pedal position φ and the gear g into theshort-term memory 23. As long as no gear change occurs, the programskips after step 36 to step 45, as indicated by the symbols II--II, andin the above-described manner again determines the instantaneous workingpoint A of the engine. Only once a gear change has been made does theprogram again run from step 36 to steps 37 and 38, in order to determinethe standardized power Pn. As soon as the transmission 12 has beendownshifted, or reengaged in the same gear, a comparison of thestandardized power prior to and following the shifting operation is notrequired. The program therefore skips after step 40 to step 45, asindicated by the symbols II--II, in order to determine and monitor theinstantaneous operating state of the engine 11. After program step 43 aswell, the program always skips to step 45 if the comparison of thestandardized power Pn prior to and following the upshifting indicatesthat the most recently measured standardized power Pn is less than thestandardized power (Pn) n determined prior to the upshifting of thetransmission 12. In these cases, accordingly, the previously determinedworking point is not fed into the threshold value memory 24, because thedrive power required for operation prior to the upshifting was no longerattained following the upshifting. In the continuous monitoring of theworking point A of the motor 11, the program always skips step 47, thatis, the step for flashing an upshifting signal, if it is determined thatthe ascertained working point A is in the favorable fuel consumptionzone I of the threshold value memory 24, the memory locations of whichare occupied by a "0".

In the exemplary embodiment of FIG. 3, the working point A wasdetermined in second gear at an engine speed n=4000 min⁻¹ and a gaspedal position φ=32°. The memory location in the memory matrix 24a ofthe threshold value memory 24 assigned to this working point A forsecond gear is below the threshold line a. The memory location of thethreshold memory 24 associated with the working point A for second geartherefore has a content of "1". This means that in accordance withprogram step 47, an upshifting signal is sent to the upshiftingindicator 25. The characteristics graph of FIG. 4 shows that at thisworking point A, the motor 11 produces an output P=30 KW and has a fuelconsumption rate of 11.5 liters per hour. Now as soon as the driverobeys the instruction to shift upward, the speed n of the motor 11 willdrop in third gear to approximately 2900 min⁻¹, as shown in FIG. 4, andthe gas pedal will be depressed further, as far as φ=40°, in order toattain the same power. The fuel consumption at the new working point A'accordingly drops to 9.5 1 per hour. Assuming that the threshold valuelines a for the various gears have approximately the same course, it canbe inferred from FIG. 3 that the new working point A' is now in thefavorable fuel consumption zone I for third gear in the threshold valuememory 24. From FIG. 4, it is also apparent that upon a furtherupshifting to fourth gear (indicated by broken lines), the engine speedn drops so far that the previously required drive output of 30 KW can nolonger be produced by the engine 11.

The invention is not restricted to the exemplary embodiment, because themethod for detecting the optimal gear in terms of fuel consumption canbe embodied in still further ways by means of additional program steps.The following method steps, however, are essential. During a drivendistance, the output speed n₁ of the transmission 12, or a correspondingvariable such as the speed of a drive wheel, is measured in common withthe engine speed n and the gear engaged at that time is determined fromthese data. The measured values for the engine speed n and for theoutput speed n₁ as well as the value φ of the gas pedal position arefurthermore continuously stored in memory for brief periods. Each timean upshifting of the transmission 12 is completed, the new standardizedpower Pn2 is compared with the standardized power Pn1 ascertained priorto the upshifting, and if the new standardized power Pn2 is the same orgreater, the values for the engine speed n and gas pedal position φmeasured and stored in memory prior to the upshifting are fed into aregion of a threshold value memory associated with the gear that hadbeen engaged prior to the upshifting.

In this manner, during the drive, numerous threshold values A1, A2 . . ., which divide the favorable operating range of the engine 11 in termsof fuel consumption from the unfavorable operating range, are recordedin the threshold value memory 24, laid out in the regions for theindividual gears, as a consequence of repeated upshifting of thetransmission 12 to various gears at various engine speeds n and variousgas pedal positions φ. With the exception of reverse gear and thehighest gear, the ascertained threshold values for each gear arerecorded in the threshold value memory 24 in a memory matrix 24a laidout in an arbitrarily fine gradation in terms of the engine speed n andthe gas pedal position φ. Prior to the first drive and at the beginningof the learning phase of the shift indicator, three different basicstates of the memory matrices can be assumed. In one case, all thememory locations are erased, or in other words are occupied by an "0".After each successful shifting operation, the microcomputer setsspecialized regions of the matrix to "1" and thus successively builds upthe zone II as shown in FIG. 3. In the second case, all the memorylocations are initially set. After each successful shifting operation,the zone II is reduced in size by erasing specialized matrix regions.However, it is equally possible, in a modification of the exemplaryembodiment, for various basic values to be fed into the threshold memory24 prior to the beginning of a drive, for instance by the manufacturer,in the form of a temporarily coarsely defined characteristic curve; thenduring the first drive these values can already be used for anupshifting indicator, and then replaced in memory by more accuratethreshold values during the drive, in that further memory locations inthe memory matrix 24a are assigned a "1" by means of the program of themicrocomputer 19. By means further program steps, individual thresholdvalues recorded in the threshold value memory can also be cancelledagain, if during later drives the standardized power Pn₂ following anupshifting of the transmission 12 at these threshold values repeatedlyfails to attain the standarized power Pn1 prior to the upshifting. Inthis manner, it is possible to correct the threshold value line a (FIG.3), by means of the driving behavior of the driver. This is necessaryfor instance if a different driver no longer shifts upward as quickly oraccelerates as far as a previous driver. The moving speed couldaccordingly drop so far that the motor 11 is no longer capable ofdeveloping the required driving power, thus necessitating shifting backdown again. An upshifting indication should be provided, however, onlywhenever the drive power in the next higher gear does still permit anacceleration of the vehicle in every case. To this end, theinstantaneous values fo the engine speed n and the gas pedal position φare each compared with the threshold values stored in the thresholdvalue memory 24 for the particular gear engaged at the time, and anupshifting indication is triggered only if the instantaneous values nand φ exceed the threshold values in the direction of the unfavorablefuel consumption zone II.

On the condition that the two speeds u_(1d) and n_(1c) differ onlyinsignificantly from one another, it is possible to detect astandardized power merely by calculating the difference between thespeeds (n_(1a) -n_(1b)) or (n_(1c) -n_(1d)).

Nor is the circuit for performing the method restricted to the exemplaryembodiment. For instance, instead of the gas pedal position, theposition of the throttle, or in a fuel-injected engine the position ofthe governor rod of a fuel injection pump can be detected in order toascertain the working point. Instead of the speed transducer 22 on theoutput shaft of the transmission 12, a speed transducer for an anti-skidbrake system located on one or more of the drive wheels can also beused. A tachometer transducer already present in a motor vehicle canalso be used for this purpose. For the engine speed n, instead of thetransducer 21 it is also possible to use a dead center transducer,ignition timing mark transducer or the high-voltage pulse during theignition process, so that in retrofitting a vehicle with the circuitaccording to the invention the existing transducer devices can be usedas needed, with appropriate adapters, in order to ascertain the requiredoperating data. The short-term memory 23 can be a transient memorygenerated by software, such as a shift register with sufficient memorycapacity; however, it can also be realized in common with theintermediate memory in the form of a RAM, in that the stored data arecyclically overprinted. The beginning of a shifting operation at thetransmission 12 can be recognized by the microcomputer 19 in that withthe vehicle speed remaining virtually the same, the engine speed rapidlydecreases or increases. It is also possible, however, to detect thebeginning and end of a shifting operation by means of a clutch switch onthe transmission coupling and to supply this to the microcomputer 19 viaa further input.

The essential advantage of the method according to the invention overthe known methods for determining the optimal gear of a motor vehicletransmission in terms of fuel consumption is that regardless of the loadstatus, the grade of the roadway, and air and frictional resistance, andregardless of the gear ratios of the gear steps and the power rating ofthe engine of the vehicle, the threshold values are determinedseparately for each gear. The system is intelligent, i.e., is capable oflearning, because each time the transmission is shifted upward when thepower is at least equally high after the upshifting operation, more andmore threshold values are fed into the threshold value memory 24 insuccession, so that as the driving time increases a finely graduated orcontinuous threshold value curve a for upshifting without reducing thedrive power is formed incrementally. Thus the sensitivity and accuracyof the upshifting indicator increases along with the number ofsuccessful upshifting operations, and even later the upshiftingindication adapts to another kind of driving behavior or a change inpower brought about for instance by used-up spark plugs, adjustment ofthe carburetor or injection pump, or changes in the ignition timing.

Instead of a visual and/or acoustical upshifting indicator, however, itis also possible within the scope of the invention for the upshiftingsignal emitted by the switching device to be used for shifting anautomatic transmission. Downshifting of the transmission can also berealized, with a downshifting signal being generated by the switchingdevice whenever, with the gas pedal depressed virtually fully and at anengine speed of less than 1500 min⁻¹, a negative acceleration isdetected. Furthermore, in this case, the program steps 32 through 34 ofthe microcomputer program for detecting the engaged gear in accordancewith FIG. 2 can be dispensed with, if in automatic transmissions theindividual gears are ascertained by correspondingly assigned switches.

What is claimed is:
 1. Method of intelligently determining andindicating the gear of a motor vehicle drive which optimizes fuelconsumption without decreasing the drive power, comprising the stepsof:(a) measuring the driving speed (n₁) of the vehicle (10) and theengine speed (n), and determining, from the ratio of said speeds, whichgear (g) is engaged at that time; (b) continuously storing in ashort-term memory (23) the instantaneous measured values of the drivingspeed (n₁) and the engine speed (n) as well as the gas pedal deflectionangle (φ), said engine speed and deflection angle values (n, φ) togetherdefining a working point pair (A1, A2, . . . ); (c) deriving from thevalues of the driving speeds (n₁) measured in brief succession, astandardized power value (Pn) and temporarily storing said power value;(d) after each completed upshifting of the transmission (12), deriving anew standardized power value (Pn₂) and comparing said newly derivedvalue with the standardized power value (Pn₁) determined prior to theupshifting; and (e) testing whether the new standardized power value(Pn₂) is at least equal to said value (Pn₁) prior to the upshifting,and, if so, copying from said short-term memory (23) the values, forengine speed (n) and gas pedal deflection angle (φ) which were measuredand stored therein prior to said upshifting, into a threshold valuememory (24) at a working point location (A) associated with the gear (g)out of which shifting has been performed, (f) defining, for the gear (g)out of which shifting has been performed, as an engine operating zone(II) that is unfavorable in terms of fuel consumption, all working pointpairs in which the engine speed is greater than said copied engine speedvalue and the deflection angle value is less than said copied deflectionangle value; and g) signaling on an upshift indicator (25) thedesirability of an upshift each time after said instantaneous valuesdefine a working point (A) falling within said unfavorable fuelconsumption zone (II).
 2. Method according to claim 1, wherein said stepof deriving a standardized power value comprises forming said value fromthe difference between the driving speed values measured in briefsuccession and squared (n_(1a) ² -n_(1b) ²).
 3. Method according toclaim 2, wherein for each gear (g), in a memory matrix (24a) associatedwith this gear in the threshold value memory (24) the ascertainedthreshold values (A1, A2) are recorded in specific memory locations laidout in steps in accordance with engine speed (n) and gas pedal position(φ).
 4. Method according to claim 3, wherein before the beginning of thefirst drive, various basic values are fed in the form of a coarselydefined characteristic curve by erasing memory locations in zone (I) andby setting memory locations in zone (II).
 5. Method according to claim1, wherein during a driving distance, by means of repeated upshifting ofthe transmission (12) in the various gears (b) at different enginespeeds (n) and different gas pedal positions (φ), a plurality ofthreshold values (A1, A2) are recorded in the threshold value memory(24) laid out for the individual gears (g), these threshold valuesseparating in the operating zone I of the engine (11) that is favorablein terms of fuel consumption from the operating zone II of the engine(11) that is unfavorable in terms of fuel consumption.
 6. Methodaccording to claim 1, wherein before the beginning of the first drive,all the memory matrices are erased or set and consequently are occupiedby a "0" or "1", respectively.
 7. Method according to claim 1, whereinindividual threshold values (A1, A2) recorded in the threshold valuememory (24) are erased once again, if at these threshold values, duringlater drives, the standardized power (Pn₂) following upshifting of thetransmission (12) repeatedly no longer attains the standardized power(Pn₁) determined prior to the upshifting.
 8. Method according to claim1, wherein the instantaneous values for the engine speed (n) and the gaspedal position (φ) are each compared with the threshold values (A1, A2)stored in the threshold value memory (24), for the particular gear (g)engaged at that time and that an upshifting signal is triggered wheneverthe instantaneous values (n, φ) exceed the threshold values in thedirection toward the operating zone (II) that is unfavorable in terms offuel consumption.
 9. Intelligent optimum-gear indication circuit for amotor vehicle, comprisinga position transducer (18) measuring the gaspedal deflection angle (φ), a speed transducer (21) measuring the enginespeed (n), a further speed transducer (22) measuring the driving speed(n₁), an upshift indicator (25), and an evaluation circuit device (20)connected to an input of said upshift indicator and to outputs of eachof said transducers (18, 21, 22) and havinga short-term memory (23)storing a limited number of recent instantaneous transducer outputvalues, said engine speed and deflection angle values together defininga working point pair (A),and an alterable threshold value memory (24),containing, for each gear step of the transmission (12), dataclassifying each working point pair (A) alternatively into a favorablefuel consumption zone (I) or an unfavorable fuel consumption zone(II),said evaluation circuit device (20) detecting when each gear shiftoccurs, comparing power before and after each upshift, updating saidalterable threshold value memory (24) each time an upshift isaccomplished without loss of power, based upon values stored in saidshort-term memory (23), thereby learning where the boundary between saidfuel consumption zones lies for each particular combination of driver,road conditions, and engine conditions, and actuating said upshiftindicator (25) whenever said instantaneous value define a working point(A) falling within said unfavorable fuel consumption zone (II). 10.Circuit according to claim 9, characterized in that the threshold valuememory (24) comprises one memory matrix (24a) associated with each gear(g), and the memory locations thereof which are located in the operatingzone (II) that is unfavorable in terms of fuel consumption have adifferent content from the memory locations assigned to the zone (I)that is favorable in terms of fuel consumption.